Polymeric compositions stabilized against heat, aging and light with saccharine derivatives



r 3,193,520 United States Patent ice PM My 6,

3,193,520 The application of the stabilizing compounds of my POLYMERICCOMPOSHEONS STABE'EZED AGAINST EEAT, AGING AND LIGHT -W1TH SACCHARINEDERIVATIVES Cornelia Caldo, Terni, Italy, assignor to MontecatiniSocieta Generals per lllndustria Mineraria e Chimica,

a corporation of Italy N0 Drawing. Filed July 31, 1961, Ser. No. 127,850Claims priority, application lltaly, Aug. 2, 1950, 13,836/ 60 5 Claims.(Cl. 260-453) The present invention relates to stabilized polymericcompositions of crystalline poly-alpha-olefins and to a process forstabilizing fibers, films and other manufactured articles made from suchcrystalline olefin polymers, particularly polypropylene.

It is known that polyolefin materials undergo a certain degradationduring hot working, particularly in the presence of atmospheric oxygen.It is also known that articles manufactured from crystalline polyolefinsare sensitive to the action of light and to thermal treatment.

This degradative action can be reduced by the addition of variousspecified protective substances to the polymer, generally during thepreparation of fibers, films, etc. For this purpose small proportions ofsuch compounds as amines, aminophenols, chelates of transition metalse.g., organo-tin compounds, triazole compounds, zinc compounds,dithiocarbamates, phenols, phosphites, mercaptans, oxirnes,polyquinolines, sulfur derivatives, etc., have been used.

An object of this invention is to provide novel stabilizedcompositionscomprising a crystalline poly-alpha-olefin.

Another object is to provide novel methods for obtaining such stabilizedcompositions.

Additional objects will become apparent hereinafter.

We have now surprisingly found that a,,8-benzoisothiazolone-l-dioxidesaccharine and certain nitrogen-substituted derivatives thereof exert ahigh stabilizing action against the action of heat and, in severalinstances against aging and of the action of light when mixed with thecrystalline olefin polymer in an amount up to 2% of the weight of thepolyolefin.

These compounds also act as stabilizers for compositions comprisingcrystalline polyolefins and basic nitrogen compounds such as thoseformed from polypropylene and polyalkyleneimine disclosed in US. patentapplication, Serial No. 702,430, filed on December 12, 1957, now PatentNo. 3,107,228, which compositions produce textile fibers having improvedtinctorial characteristics.

In accordance with the present invention polymeric compositions areobtained which are stable against the action of heat, aging and light,which compositions comprise a crystalline polyolefin and an organicstabilizer comprising a,,8-benzoisothiazolone-l-dioxide (saccharine) orits N-substituted alkyl, aryl, alkaryl, or ketonyl derivatives in anamount from about 0.02 to 2% by weight of the overall composition. Thepresent invention also contemplates a process for stabilizingcrystalline polyolefins, e.g., polypropylene, against the action ofheat, aging and light, comprising adding to the polyolefin compositionin an amount from about 0.02% and 2% by weight (preferably 0.2%) of thepolyolefin of a, 3-benzoisotldazolone-1- dioxide (saccharine) or itsnitrogen-substituted derivatives such as e.g., N-methylsaccharine,N-ethylsaccharine, N-phenylsaccharine and N-acetonylsaccharine.

invention is generally carried out by mixing such compounds with thepoly-alpha-olefin, e.g., polypropylene while agitating.

Of course, the stabilizers can also be added by other methods such ase.g., by mixing the polyolefin with a solution of the stabilizer in asuitable solvent and then evaporating off the solvent; by adding thestabilizer to the polyolefin at the end of the polymerization; etc.

It is also possible to obtain the benefits of the stabilizing action byapplying the stabilizing compounds directly onto the manufacturedarticle, e.g., by immersing the article in a stabilizer solution ordispersion and then evaporating oif the'solvent or dispersing vehicle.

The stabilizing compounds of the present invention exhibit a goodcompatibility with molten polyolefins and have no staining actionthereon;

The stabilized compositions of the present invention macromolecules asdefined -by Natta, e.g., U.S. Patent Example 1 In a Werner type mixer ahomogeneous mixture is prepared at room temperature from 9.98 kg. ofpolypropylene (prepared with the aid of stereospecific catalysts andhaving an intrinsic viscosity determined in tetrahydronaphthalene at 135C., of 1.34, a residue from heprtane extraction of 93.4%, and an ashcontent of 0.028%) and 20 g. .of a,fi-benzoisothiazolone-l-dioxide.

The polymer stabilizer mix, when subjected to melting in a test tubekept in a thermostatic bath at 250 C. for 10 minutes, produces avirtually colorless molten mass.

The mix is spun in a melt spinning device under the followingconditions:

Screw temperature 200 C.

Head temperature 200 C. Spinneret temperature 230 C. Spinneret type 60/0.8 x 16 mm. Maximum pressure 45 kg./cm. Winding speed 300 meters min.

The fibers are stretched with a stretching ratio of 1 to 5.3 at 130 C.The serimetric characteristics of the fibers obtained are as follows:

Tenacity g./den 4.36

Elongation percent 26.2

In the transition from polymer to fiber, the intrinsic viscosity islowered to 77% of the initial value, whereas the intrinsic viscosity ofa fiber obtained from the same polymer without addition of stabilizer islowered to 74.5% of the initial value.

The stabilized yarn, when exposed for 15 hours to the action of heat inan oven provided with air circulation at C. (accelerated thermal agingtest) remains practically unaltered in its characteristics.

After exposure to an ultra-violet mercury lamp for 20 hours thestabilized yarn maintains 37% 0f the initial tenacity, while with thenon-stabilized yarn control the tenacity is reduced to only 32% of itsinitial value.

Example 2 In a Werner-type mixer a homogeneous mixture is prepared atroom temperature from 9.95 kg. of poly propylene (prepared withstereospecific catalysts and hav- ElIlg' an intrinsic viscosity of. 1.34as determined in.tetra-.

hydronaphthalene at 135 C., a residue after heptane extraction of 94.3%and. an ash content of 0.028%) and 50 g. of a,,B-benzoisothiazolone-ldi-oxide.

The polymer-stabilizer mix, when subjected to melting I 7 in a test tubekept in a thermostatic. bath at 250 C. for

10 minutes, produces an almost colorless molten mass. The mix is spun ina melt spinning device under the following conditions: I

The fibers are stretched with a stretching ratio of 1 to 5.3 at 130 C.The se-r-imetrical characteristics of the yarn obtained are: p

Tenacity g./den 4.36

Elongation .percent 26.2

'In the transition from polymer to fiber, the-intrinsic viscosity islowered to 81% of its initial value, whereas the intrinsic viscosity ofa fiber obtained from the same polymer without addition of stabilizer islowered to.

74.5 of its initial value.

The stabilized yarn when exposed for 15 hours to the action of heat inan oven provided with air circulation at "120 C. (accelerated thermalaging test), remains al- 3 5 most unaltered in its characteristics.

After exposure to an ultra-violet mercury lamp for .20

hours the stabilized yarn maintains 40% of its initial tenacity, whereasthe tenacity of the non-stabilized yarn control is reduced to 32% of itsinitial value.

p I Q i V Example 3' V In a Werner type mix-er a homogeneous mix isprepared at room temperature from 9.90 kg. of polypropyl-.

ene (prepared with the aid of stereospecific catalysts and having inintrinsic viscosity of 1.34-determined in tetra-- The mix is spun in-amelt spinning device under the.

following conditions: 7 V

. Elongation 4 Screw temperature 220 C.

. Head temperature 220 C. Spinneret temperature 230 C. Spinneret type/08 x 16 Maximum pressure 40 kg./cm. Winding speed 300 meters/min.

The fiber is stretched with a stretching ratio of 1 to 5.3 at 130 C. Theserimetrical characteristics of the fiber obtained are;

Tenacity g./den 4.02 "percent" 23.5

In the transition from polymer to fiber, the intrinsic viscosity islowered to 78.5% of its initial value, whereas the intrinsic viscosityof a fiber obtained from the same polymer without addition of stabilizeris lowered to 74.5% of its initial value.

The stabilized yarn, when exposed for 15 hours to the action of heat inan oven provided with air circulation at 7 C. (accelerate-d thermalaging test), remains almost unaltered in itscharacteristics.

Afiter exposure. to an ultra-violet mercury 'lamp for 20 hours thestabilized yarn maintains 44% of its initial tenacity, whereas thetenacity of the non-stabilized yarn control is reduced to 32% of itsinitial value.

Variations can of course be made without departing from the spirit of myinvention.

Having thus described my invention, what I desire to secure and herebyclaim is:

'1. A polymeric composition stabilized against heat, aging and light,comprising a crystalline polypropylene consisting prevailingly ofisotactic macromolecules and a stabilizing amount of an organicstabilizer selected from the group consisting ofu,fi-benzoisothi-azolone-l-dioxide, N-alkylri-benzoisothiazolone-1'dioxide, N-aryl-u fi-benzoisothiazolone 1-dioxi-de,N-alkaryl-a,B-benzoisothiazolone-l-dioxide, andN-kGtOnYl-0a,,B-b6IlZOiSOthiE1ZOlO11B-1- dioxide. a

2. The polymeric. composition of claim 1, wherein the amount ofstabilizing organic compound is from about 0.02 to 2% by weight of thepolypropylene.

' 3. The polymeric composition of claim 1, wherein the amount ofstabilizing organic compound is from about 7 40.2 to 1% by weight of thepolypropylene.

4'. The product of claim 1 in film form. V 5. The product of claim 1 infiber form.

7 References Cited by the Examiner UNITED STATES PATENTS 2,985,617 5/61Salyer et a1. 26045.95

LEON J.' BERCOVITZ, Primary Examiner.

- MILTON STERMAN, Examiner.

1. A POLYMERIC COMPOSITION STABILIZED AGAINST HEAT, AGING AND LIGHT,COMPRISING A CRYSTALLINE POLYPROPYLENE CONSISTING PREVALINGLY OFISOTACTIC MARCOMOLECULES AND A STABLIZING AMOUNT OF AN ORGANICSTABILIZER SELECTED FROM THE GROUP CONSISTING OFA,B-BENZOISOTHIAZOLONE-1-DIOXIDE,N-ALKYL-A,B-BENZOISOTHIAZOLONE-1-DIOXIDE,N-ARYL-A,B-BENZOISOTHIAZOLONE-1-DIOXIDE,N-ALKARYL-A,B-BENZOISOTHIAZOLONE-1-DIOXIDE, ANDN-KETONYL-A,B-BENZOISOTHIAZOLONE-1DIOXIDE.